Continuous processing of flexible materials



' July 7 1970 H. DUIS 3,518,847

CONTINUOUS PROCESSING OF FLEXIBLE MATERIALS I Filed April 14, 1967WVENTO HERWARD DLHS United States Patent 3,518,847 CONTINUOUS PROCESSINGOF FLEXIBLE MATERIALS Her-ward Duis, Krefeld-Urdingen, Germany, assignorto Job. Kleinewefers Sons, Krefeld, Germany, a corporation of GermanyFiled Apr. 14, 1967, Ser. No. 636,232 Claims priority, applicationGermany, Feb. 18, 1966, K 58,483 Int. Cl. D06f 39/10 US. Cl. 68-48 2Claims ABSTRACT OF THE DISCLOSURE An apparatus useful for the continuousprocessing of flexible materials such as cotton textiles which comprisesa pressure chamber capable of holding a treating fluid at conditions inexcess of 100 degrees C. and at a pressure above 1 atmosphere, whereinan inlet permits introduction of the flexible material into the chamberbelow the level of the fluid, and means are employed to convey thematerial through the chamber and out of the chamber continuously whilemaintaining the flexible material below the level of the fluid in thechamber. The apparatus additionally contains recirculating means forwithdrawing the fluid from the chamber, filtering the fluid andrecharging it back to the chamber while simultaneously supplyingadditional fluid to maintain the Volume at any given level in thechamber.

BACKGROUND OF THE INVENTION Flexible materials such as textiles areoften treated with chemicals. A primary example of such chemicaltreatment, illustrative of the nature of the present invention, is theprocess of bucking and/ or bleaching textiles such as cotton. Thebucking process involves a method whereby cotton is freed of stilladhering hull and impurities, while the fibre is also made morereceptive to the actual bleaching process. Bleaching, of course, is aprocess to whiten the flexible material. Other natural and syntheticflexible materials such as rubber, nylon, Wool, etc. are also chemicallytreated during manufacture.

These processes, and others common to the industry, have been carriedout in high-pressure containers. In some instances, more than oneoperation is carried out simultaneously in a single chamber, while inother instances several succeeding chambers provide for a series ofsuccessive operations on the flexible material.

If the processes of bucking and bleaching of cotton is accomplished inseparate pressure containers, a disadvantage is encountered when theprocesses are run continuously, in that the bucking (and the dissolvingof the hull) takes substantially longer time than does the bleachingstep. This difference in time results in the necessity that the separatesteps be performed at different speeds, or that the longer bucking stepsbe repeated two or more times. An alternative proposal to construct asubstantially larger pressure container to increase the residence timeis uneconomical because of the substantially greater capital investmentwhich simultaneously limits any use of this equipment for more than thissingle purpose.

A recently developed theory to explain the bucking process, and itsinherent delay, is based upon the fact that the cotton material entersthe pressure at a substantially lower temperature than that maintainedinside the chamber. Upon enry, the fabric is immediately subjected tosteam condensation which causes a thinning or dilution of the surfaceliquids, thereby reducing the con- 3,518,847 Patented July 7, 1970centration of the reactant and causing a slow down in the rate ofreaction. This dilution effect additionally causes the use ofsubstantially greater quantities of liquids because of their reducedeffectiveness, and use of regenerating equipment to restore thereactants is costly and time consuming.

Accordingly, it is an object of this invention to provide an apparatusfor treating flexible materials with chemicals in a most efficientmanner.

A more particular object of this invention is to provide an apparatususeful for the process of bucking and/or bleaching of textiles such ascotton.

A specific object of this invention is to provide apparatus which issuitable for continuous bucking and leaching of cotton in two successivestages, wherein there exists no substantial difference in residence timebetween the two stages.

Other objects will become apparent to those skilled in the art upon acareful reading of the description of the invention provided herewith.

It has been found that the objects of this invention may be accomplishedin the following manner. A process for treating flexible materials hasbeen discovered which comprises the steps of passing a flexible materialthrough a chamber containing a body of treating fluid maintained at asuitable temperature and pressure, wherein the material enters thechamber at a point below the level of the fluid therein and is passedthrough the chamber to ac complish the treatment without permitting thematerial to rise above the fluid level. The process is further improvedby the simultaneous withdrawal of a portion of the treating fluid,filtering this withdrawn portion and returning the filtered fluid to thechamber while adding suflicient additional fluid to maintain the levelof the fluid above the textile. Other embodiments and modifications aredescribed hereinafter.

It has also been discovered that the process of treating flexiblematerials in a continuous manner may be effected by the use of anapparatus comprising a pressure chamber suitable for holding a body offluid and containing means for maintaining the temperature of the fluidat certain temperature and pressure conditions which may be decided upondepending upon the treatment process. The apparatus further contains aninlet for introducing the flexible material, conveying means forconveying the material through the chamber and outlet means forwithdrawing the material from the chamber. The apparatus still furthercontains means for withdrawing a portion of the fluid, filtering thisportion and recharging the portion back into the chamber. Finally, theapparatus contains supply means for adding sufficient fluid to thechamber to maintain a constant volume within the chamber, therebycompensating for losses of fluid occasioned by either the filtrationstep or the removal of the flexible material.

The invention will be further described by Way of example with referenceto the accompanying drawings, in which the figure schematicallyillustrates the apparatus and process of this invention in a specificembodiment.

With reference to the figure, in a vat type pressure vessel or chamber1, the pressure tight inlet 2 for leading the flexible material 3through the chamber is installed in the middle of the vat, or in a lowerpart of the vat, and the liquid level 4 is maintained sufficiently highwith respect to the chamber so that the path of the flexible material inthe chamber does not rise above this liquid level. The flexible material3, after being introduced into the chamber 1 by the inlet 2, is conveyedthrough the body of the fluid contained in the chamber 1 by means ofconveying means such as guide rollers 5 which regulate the length ofpassage of the flexible material. The guiding or conveying meanstransfers the flexible material to an outlet 6 which withdraws theflexible material from the chamber. By a steam supply 18, the necessarypressure over atmospheric pressure (and a resulting temperature over 100degrees C.) can be maintained. To optimize the efficiencies of the heatsupplied by the steam, it is sometimes desirable to pre-heat the fluid(not shown). It is also possible to maintain the temperature of the bodyof the fluid in the chamber 1 by means of a heating coil or heatexchanger 7 which is positioned in the interior of the chamber. Byinstallation of the heat exchanger 7 within the pressure chamber 1 in aposition eccentric to the center of the chamber, forced convection and abetter heat performance is achieved.

Since the normal operation of chemical treatment of flexible materialsmay and oftentimes does involve production of impurities or byproducts,which are undesirable, an embodiment of this invention is provided toremove these undesirable materials. Referring again to the figure, aconduit 8 is attached to the chamber 1 to permit flow of the fluid intothe cleaning apparatus 9, which in this instance, is arranged as apressure vessel, whereby the fluid is filtered by passage through afilter 10, and from there is returned to the chamber 1 by means ofconduit v11 through a circulating pump 12. The cleaning apparatus 9 isprovided with an easily exchangeable filter 10, whereby a use of aquick-opening valve 13 permits the removal and cleaning of the filters10.

In addition, the flexible material 31 passing through the chamber 1oftentimes picks up a certain amount of the processing fluid, so thatthis fluid has to be replaced, in an ideally continuous manner. This maybe done as shown in the figure by the addition of more fluid through apressure pump 16 over a check valve 17. The pump is automaticallyregulated by a liquid level regulator 14 over an amplifying device 15.

The use of the apparatus described in the figure in a specific processwhereby cotton textile is subjected to the bucking process demonstratesthe efficiencies of the present invention. Due to the fact that thecotton fabric did not contact the steam atmosphere supplying thetemperature and pressure conditions, but rather, was maintained belowthe liquid surface, the cotton was immediately heated to a very hightemperature approximating that of the temperature of the fluid in thechamber. The cotton material was passed through the inlet and conveyedthrough the body of the solution, where upon it was withdrawn from thechamber through the outlet. Simultaneously with this bucking treatment,a portion of the treating fluid was continuously removed from thechamber and passed through the filter, thereby removing impurities whichwere caused by dissolving the detached hull and fibres. -In one specificinstance, operation of the bucking process using the apparatus of thisinvention resulted in a reduction of the time necessary tosatisfactorily treat the material from an average residence time at theparticular rate of fabric travel of three minutes down to one-halfminute or less. This reduction time provided many advantages to theproduction of cotton textiles since an efficient and rapid removal offibres and hulls from the cotton was effected without subjecting thecotton to substantially high temperatures for any considerable length oftime. In addition, the rate of bucking was sulficiently high so as topermit a subsequent bleach.- ing process to be effected without anyvariations in the rate of travel of the textile material. Prior to thistime, such an accomplishment was not possible.

Due to the versatility of the present apparatus, it is possible toutilize this same apparatus without modification for a wide variety ofother chemical treating operations employed in the manufacture offlexible materials. For example, this same apparatus describedhereinabove was employed to bleach a cotton fabric of the type treatedin the bucking process operation described above. The

versatility of the apparatus was proved by these experiments in that asubstantial and costly problem of chlorine gas escape was obviated.Normally, in the cotton bleaching process, the use of chlorine dioxidehas not been used, even though this material is relatively inexpensive,because of the severe problems of chlorine gas escape when the bleachedtextile is removed from the treating chamber. Furthermore, substantialcorrosion if even the most resistant metals is found when the chlorinedioxide is allowed to vaporize in a steam atmosphere to form chlorinegas.

In the operation of the present apparatus, however, these problems wereobviated in a satisfactory manner. In the specific operation of thepresent apparatus for bleaching cotton textiles, the apparatus asdescribed in the figure was again employed. The chamber 1 was completelyfilled with the treating buid so that the liquid level 4 was at the verytop of the chamber 1. The cotton fabric 3 to be bleached was againintroduced through the inlet 2 and was conveyed through the fluid by ameans of a conveying means 5 to an outlet 6 wherein the bleachedmaterial was withdrawn. The sole source of heat for this operation wasthe heat exchanger 7, since the stream inlet 18 was closed off and notin operation. As was described in the bucking process example, the fluidwas withdrawn through the conduit 8 through the filtering device 9,wherein the fluid was filtered in the filter 10 and returned throughconduit 11 by means of pump 12 to the chamber 1. The pressure pump 16through check valve 17 was modified by adjusting the liquid levelregulator 14 to provide a full chamber at all times. Thus there was nosteam atmosphere present in the chamber and the formation of chlorinegas from the liquid solution of chlorine dioxide was prevented. As thematerial 3 was withdrawn through the outlet 6, evolution of the chlorinegas caused by evaporation of entrained aqueous chlorine dioxide wasprevented by merely running the textile 3 through a canal (not shown)wherein water was sprayed to cool the textile and dissolve the chlorineprior to its evaporation.

The filter 10 contained within the pressurized filter 9 may be cleanedby removal from the pressurized filter 9. A hinge 30 is provided on oneend of the pressurized filter 9 to permit that end to pivot about saidhinge 30. Latch 32 insures that the filter is properly closed duringoperation. Handle 34 is provided to permit access to the filter 10.

Thus it can be seen that the instant apparatus is admirably suitable foruse in a substantial number of processes wherein flexible materials aretreated with chemical additives. The skilled worked will find manymodifications and variations of the process which will be suitablyadapted to his particular needs without departing from the spirit of theinvention.

Having thus described the invention herein, what is claimed is:

1. Apparatus useful for continuous chemical treatment of flexiblematerials comprising in combination: a pressure chamber suitable forholding a body of fluid with means for maintaining the temperature ofsaid fluid in excess of degrees C. at a pressure in excess of 1atmosphere; an inlet for introducing the flexible material into thechamber; conveying means for conveying said material through the chamberfrom said inlet; an outlet for withdrawing said material from saidconveying means to a point outside the chamber; recirculating meansincluding a pressurized filter for withdrawing a portion of the fluidfrom said chamber, filtering said portion and recharging said filteredportion back into said chamber; supply means for adding sufficient fluidto said chamber to maintain a volume of fluid within said chamber abovethe highest point of travel of said flexible material, said pressurizedfilter being equipped with shutoff valve means to stop flow of fluidinto said filter, and said pressurized filter containing means forwithdrawing the filter portion of said pressurized filter for cleaning.

2. The apparatus of claim 1 wherein said supply means 5 comprises aninlet valve attached to and controlled by a pressure pump which isactivated by a liquid level regulator adjusted to maintain a volume ofsaid fluid within said chamber above the highest point of travel of saidflexible material.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 6/1956 France.

WILLIAM 1. PRICE, Primary Examiner US. Cl. X.R.

